Evaluation of Vocal Cord Paralysis Following Lung Transplantation

ABSTRACT

Objectives

Vocal fold paralysis or paresis (VCP) is a possible complication of lung transplant surgery. The otolaryngology service is often consulted to evaluate these patients via laryngoscopy and flexible endoscopic evaluation of swallowing (FEES). This study aims to quantify vocal fold pathologies via direct visualization.

Methods

A retrospective chart review was conducted at a single quaternary medical center over a 3.5‐year period, from December 2019 to May 2023. The presence of abnormal laryngoscopic findings in these patients was reviewed with specific descriptions of vocal fold findings reviewed and described in further detail.

Results

A total of 78 patients met the inclusion criteria out of 127 lung transplants performed. Of these, 46 patients (59.0%) were found to have abnormal laryngoscopy findings on inpatient examination. Average time from the date of transplant to FEES examination was 10.3 days. Thirty‐two patients (42.0%) were found to have pathologies at the site of the true vocal folds. Nine patients exhibited new VCP (11.5%), 13 with granuloma (16.7%), six with hemorrhage (7.69%), and four with polyp (5.13%). Only 13 patients (16.7%) followed up with laryngology once discharged.

Conclusion

Vocal cord pathologies, including VCP, frequently occur in patients post‐lung transplantation. It is vital for the transplant team and laryngologists to monitor and help institute appropriate care and follow‐up for these patients.

Level of Evidence

2B.

1. Introduction

Lung transplantation has remained a component of treatment for select patients with end‐stage lung diseases [1]. Vocal cord paresis or paralysis (VCP) is a known complication of thoracic surgery and is often due to recurrent laryngeal nerve (RLN) injury due to its anatomical location [2, 3]. VCP has been associated with increased recurrent aspiration, risk of pneumonia, length of stay, and risk of ICU readmission, with increased risk of chronic allograft lung dysfunction (CLAD) [4, 5, 6, 7, 8]. Some studies have looked at the incidence of VCP in this patient population in cardiothoracic literature [9, 10]. Otolaryngologists are often consulted post‐transplant in the setting of VCP for evaluation and subsequent treatment. Timely evaluation of VCP is often critical due to the potentially detrimental consequences of aspiration [11]. Currently, there is a dearth of data in Otolaryngology literature regarding the incidence of vocal fold paralysis in lung transplant patients. This incidence in this vulnerable patient population is additionally important given the potential interventions that may be offered by Otolaryngology by way of timely consultation and intervention—interventions such as vocal fold medialization can potentially improve outcomes and prevent aspiration in this vulnerable patient cohort. This study aims to quantify VCP and other vocal fold pathologies in the lung transplant patient population.

2. Methods

This is a single tertiary medical center retrospective chart review from December 2019 to May 2023. Treatment outcomes were measured through recorded fiberoptic endoscopic evaluation of swallowing (FEES) and laryngoscopy physical examinations in an inpatient setting postoperatively. Findings were broken down by laterality, anatomical location, and pathology. Pathology was categorized by a trained Laryngologist. Inclusion criteria included patients who underwent unilateral or bilateral lung transplantation with subsequent inpatient laryngoscopy and evaluation performed. Demographic statistical analysis was performed using IBM SPSS Statistics, Version 23.0 (IBM SPSS Inc., Chicago, USA), and statistical nonparametric testing (Mann–Whitney U) was performed between cohorts given the sample sizes for analysis. This study was approved by the Cedars‐Sinai Medical Center Institutional Review Board.

3. Results

A total of 78 patients met inclusion criteria out of 127 patients who underwent lung transplantation in the defined time period. These patients were comprised of 42 male patients (53.8%) and 36 female patients (46.2%). Average age at the time of transplant was 61.5 years (SD = 11.0). Mean length of intubation in the patient cohort was 2.2 days (SD = 1.60). Mean number of reintubations in the cohort was 0.22 days (SD = 0.39) (Table 1).

TABLE 1.

Characteristics and findings.

Findings	No. (%) (n = 78)
Sex
Male	42 (53.8)
Female	36 (46.2)
Abnormal laryngoscopy
Yes	46 (59.0)
No	32 (41.0)
Site of pathology
True vocal cord	32 (42.0)
Type of pathology at true vocal cord
Vocal cord paralysis	9 (11.5)
Contact granuloma	13 (16.7)
Vocal cord hemorrhage	6 (7.69)
Vocal cord polyp	4 (5.13)

	Mean (range)
Age	61.5 (26–75)
Length of intubation, days	2.2 (1–8)
Time to laryngoscopy/FEES, days	10.3 (2–83)

Forty‐six patients (59.0%) were found to have abnormal laryngoscopy findings. Mean time from the date of transplant to FEES was 9.93 days (SD = 12.8). Thirty‐two patients (42.0%) were found to have pathologies at the true vocal folds. Nine patients exhibited new VCP (11.5%), 13 exhibited granuloma (16.7%), six exhibited hemorrhage (7.69%), and four exhibited polyps (5.13%). Thirteen patients (16.7%) followed up with Laryngology in the outpatient clinic postoperatively.

When further analyzing the patient cohort that developed new onset VCP (nine patients) to those that did not (69 patients), average time from transplant date to FEES examination was 11.6 days (SD = 8.82) in the VCP cohort and 10.1 days (SD = 16.0) in the non‐VCP cohort. Time from transplant to laryngoscopy did not significantly differ between patients who developed VCP and those who did not (OR 1.47, 95% CI 0.38 to 5.64). The effect size was negligible (r = 0.05; Cliff's δ = 0.07, 95% CI −0.27 to 0.39). Average length of intubation was 1.75 days in the VCP cohort and 2.25 in the non‐VCP cohort. Length of intubation did not significantly differ between patients who developed VCP and those who did not (OR 0.44; 95% CI 0.05 to 3.82). The effect size was small (r = −0.12, Cliff's δ = −0.22, 95% CI −0.57 to 0.16). Average number of reintubations was 0.50 in the VCP cohort and 0.19 in the non‐VCP cohort. The number of reintubations did not significantly differ between patients who developed VCP and those who did not (OR 2.95, 95% CI 0.64 to 13.7). The effect size was small (r = 0.18; Cliff's δ = 0.29, 95% CI −0.05 to 0.57). Of the VCP cohort, eight patients (88.9%) followed up in the Laryngology clinic post‐operatively, and five patients (7.2%) followed up in the non‐VCP cohort. Within the VCP cohort, six patients (66.7%) had left‐sided VCP and three patients (33.3%) had right‐sided VCP.

4. Discussion

VCP is an important complication of lung transplant and can have devastating effects on the recipient. We identified VCP post‐lung transplantation in 11.5% of patients. Studies in the cardiothoracic literature report incidences of VCP in the lung transplant population from 8% to 34% [9, 12, 13, 14]. Our study further corroborates this data with an incidence of 11.5% of patients in a cohort of 78. Meszarich et al. reported an incidence of 23% in a 78‐patient cohort and Seeliger et al. reported an incidence of 8.9% in a 583‐patient cohort [9, 10].

The incidences described in these studies and our study demonstrate the significant number of patients at risk of aspiration. Miles et al. demonstrated that 63% of patients aspirated silently post‐lung transplantation [14]. Seeliger et al. also reported that around 50% of the patients in their VCP cohort were asymptomatic [9]. Dallal‐York et al. also reported around 72% of patients experiencing silent aspiration. These findings of silent aspiration and asymptomatic presentations of VCP demonstrate the importance of appropriate evaluation postoperatively. Silent aspiration can lead to CLAD, thus severely limiting long‐term transplant survival [15].

The mechanism of injury leading to VCP in the lung‐transplant population is that of injury specifically to RLN, with rates of injury occurring more frequently on the left RLN and left VCP, given the longer course through the posterior mediastinum [9, 16]. Interestingly, our study also corroborates these findings as our patient cohort had 66% (n = 6) of patients demonstrating left‐sided VCP. There has also been discussion on methods to minimize RLN injury during transplantation through various surgical techniques [17]—these techniques include the use of intraoperative nerve monitoring, meticulous dissection, and leaving a small island of pulmonary artery at the insertion of the ligamentum arteriosum to reduce injury to the left RLN. Of note, this study did not observe a statistically significant difference in length of intubation or number of reintubations between VCP and non‐VCP patients. Although this finding suggests these factors may not be major contributors to VCP development, larger studies are needed to better evaluate and define this relationship.

Early treatment of new‐onset VCP has been demonstrated to decrease patient procedures as well as length of stay [18]. Recent literature further highlights the importance of multidisciplinary evaluation and early otolaryngologic involvement in this patient population. Kutler et al. recently evaluated the incidence and outcomes of vocal fold paralysis in lung transplant recipients, similarly demonstrating that VCP is a relatively common complication [19] (27.3%) with important implications for swallowing and pulmonary outcomes. In addition, Barilka et al. reported high rates of silent aspiration (54.5%) in lung transplant recipients that were frequently not detected on clinical examination alone [20], underscoring the importance of swallow evaluation such as FEES in the early postoperative period. These findings align with our study, in which a substantial proportion of patients demonstrated abnormal laryngoscopic findings and vocal fold pathology, supporting the role of routine or early otolaryngologic assessment following lung transplantation.

Management of VCP in this population also continues to evolve. Prior work by Graboyes et al. demonstrated that injection laryngoplasty can be performed safely after thoracic surgery and may improve glottic competence in patients with postoperative vocal fold paralysis [21]. Subsequent studies, including work by Barnes et al., have suggested that early injection laryngoplasty may reduce rates of pneumonia and other pulmonary complications in patients with vocal fold paralysis following cardiothoracic procedures [22]. However, the literature remains mixed. A systematic review by Pan et al. evaluating treatment of unilateral iatrogenic vocal fold paralysis did not find robust evidence that injection laryngoplasty definitively prevents aspiration [23], highlighting the need for further prospective studies. These findings suggest that while early identification and treatment of VCP may improve swallowing function and pulmonary outcomes, the optimal timing and patient selection for intervention remain areas for further investigation.

Limitations of this study included the retrospective nature of the study as well as a limited number of study subjects. Additionally, when compared to other studies, our study did not include those patients who did not undergo laryngoscopy, but the included cohort of 78 patients was still a comparable cohort. Furthermore, not all patients underwent laryngoscopic exams, and some pathology may have gone undetected. Future studies may also further elucidate optimal treatment modalities for VCP, timing, and outcomes such as hospital stay in a prospective fashion, while also examining interventions on patients with VCP.

Vocal cord paralysis is a known complication of lung transplantation. This patient population is especially vulnerable given both the type of surgery and immunocompromised state, which makes the detection of VCP in such a population of utmost importance given the potential devastating consequence of aspiration. Timely detection and intervention by trained Otolaryngologists may allow interventions, such as vocal fold injections or medialization, in the appropriately determined clinical setting. This study serves to further elaborate on the incidence of VCP in the lung transplant patient population and how it pertains to Otolaryngologists in the subsequent treatment of this high‐risk patient population.

Funding

The authors have nothing to report.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.